Sublimation printing techniques have been employed in the decoration of cloth or fabrics and involve the printing of a design on a paper backing sheet by conventional printing techniques employing sublimation inks, and then transferring such design under heat and pressure to the cloth or fabric. The decorating of 100% polyester fabrics and garments, such as 100% polyester T-shirts, employing such techniques has enjoyed overwhelming success. The sublimation inks, although somewhat dull and off-colored when printed on the paper backing sheet, have been found to produce brilliant colors and clear designs when transferred under heat and pressure to such 100% polyester fabrics or garments.
When it has been attempted to transfer designs comprising sublimation inks to other textiles however, such as 100% cotton fabrics or fabrics formed of cotton-polyester combinations, it has been found that the sublimation designs on such fabrics are weak and easily removed by laundering. It is theorized that the difficulties encountered in attempting to decorate fabrics containing cotton is attributed to the high porosity of cotton and the insolubility of the dyes in the cellulose fibers comprising the cotton.
Various techniques have been suggested in an effort to overcome the problems associated with the decoration of fabrics containing cotton. One technique involves the impregnation of such fabrics with an aqueous solution of an emulsion polymer, drying the so-impregnated fabric, and then transferring a sublimation ink design layer from a paper backing, under heat and pressure, to the so-impregnated fabric. Another technique attempted involves the spray coating of the fabric with a diluted emulsion or solution polymer and thereafter transferring a sublimation ink design layer from a paper backing, under heat and pressure, to the dried, spray-coated fabric.
Unfortunately, it has been found that the above techniques have, for the most part, been unsatisfactory in that the colors of the transferred design upon laundering become faded after a relatively short number of cycles. Furthermore, these prior art techniques require at least two separate steps in effecting the design transfer to the fabric, namely, application of the emulsion polymer to the fabric in a first step, and transferring the sublimation design to the treated fabric in a second step. The requirement of these two separate steps, especially the application of the emulsion polymer to the fabric, makes it practically mandatory that the fabrics be decorated by professionals in a commercial facility so that the emulsion polymer can be applied in the necessary amount and consistency. Moreover, the more attractive marketing approach would be to have the consumer or layman separately purchase the fabric or garment, and the sublimation transfer, and decorate the fabric or garment at home employing a conventional iron as a source of the required heat and by applying pressure to effect the transfer.
As specific examples of these prior art techniques may be included patents such as British patent specification No. 578,197. This patent thus teaches fabric impregnation with a film of organic thermoplastic material followed by application of heat and pressure to cause the material to penetrate the fabric. The specific materials employed are thermoplastic synthetic resins including polymers of vinyl compounds, polymers of acrylic acid esters and methacrylates, etc.
On the other hand, the use of cross-linkable resins for various applications has been known in the past. For example, U.S. Pat. No. 3,907,974 relates to the decoration of metal or glass articles with decalcomanias. The patentee thus teaches the use of cross-linkable resins and cross-linking agents for cross-linking the resins to form adherent decorations resistant to abrasion and chemicals. Specifically, cross-linking agents such as those having blocked isocyanate groups, for example, are shown therein. Such materials have never been employed, however, in connection with the transfer of sublimation transfer inks from backing sheets such as paper to textile fabric materials. Furthermore, it is also noted that in the past such blocked polymer materials have been employed in connection with the coating of wires, and specific reference in this regard is made to U.S. Pat. No. 3,745,138. Generally high molecular weight materials have been employed in connection with such applications. Furthermore, again, these materials have not been employed in the past in connection with processes such as those with which the present application is concerned. Finally, reference to U.S. Pat. No. 3,049,513 is also made here. This patent also relates to the use of certain isocyanate - terminated polyether based polyurethanes as coating compositions. That patent, however, employs polypropylene oxide glycols of specified molecular weights to produce an NCO-terminated urethane compositions for particular end use as coatings, preferably comprising hard urethane films.